The Tcpdump Group git mirrors - tcpdump/blob - print-chdlc.c

   1 /*
   2  * Copyright (c) 1990, 1991, 1993, 1994, 1995, 1996, 1997
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that: (1) source code distributions
   7  * retain the above copyright notice and this paragraph in its entirety, (2)
   8  * distributions including binary code include the above copyright notice and
   9  * this paragraph in its entirety in the documentation or other materials
  10  * provided with the distribution, and (3) all advertising materials mentioning
  11  * features or use of this software display the following acknowledgement:
  12  * ``This product includes software developed by the University of California,
  13  * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
  14  * the University nor the names of its contributors may be used to endorse
  15  * or promote products derived from this software without specific prior
  16  * written permission.
  17  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
  18  * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
  19  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  20  */
  21
  22 /* \summary: Cisco HDLC printer */
  23
  24 #include <config.h>
  25
  26 #include "netdissect-stdinc.h"
  27
  28 #include "netdissect.h"
  29 #include "addrtoname.h"
  30 #include "ethertype.h"
  31 #include "extract.h"
  32 #include "chdlc.h"
  33 #include "nlpid.h"
  34
  35 static void chdlc_slarp_print(netdissect_options *, const u_char *, u_int);
  36
  37 static const struct tok chdlc_cast_values[] = {
  38     { CHDLC_UNICAST, "unicast" },
  39     { CHDLC_BCAST, "bcast" },
  40     { 0, NULL}
  41 };
  42
  43
  44 /* Standard CHDLC printer */
  45 void
  46 chdlc_if_print(netdissect_options *ndo, const struct pcap_pkthdr *h, const u_char *p)
  47 {
  48         ndo->ndo_protocol = "chdlc";
  49         ndo->ndo_ll_hdr_len += chdlc_print(ndo, p, h->len);
  50 }
  51
  52 u_int
  53 chdlc_print(netdissect_options *ndo, const u_char *p, u_int length)
  54 {
  55         u_int proto;
  56         const u_char *bp = p;
  57
  58         ndo->ndo_protocol = "chdlc";
  59         if (length < CHDLC_HDRLEN)
  60                 goto trunc;
  61         proto = GET_BE_U_2(p + 2);
  62         if (ndo->ndo_eflag) {
  63                 ND_PRINT("%s, ethertype %s (0x%04x), length %u: ",
  64                        tok2str(chdlc_cast_values, "0x%02x", GET_U_1(p)),
  65                        tok2str(ethertype_values, "Unknown", proto),
  66                        proto,
  67                        length);
  68         }
  69
  70         length -= CHDLC_HDRLEN;
  71         p += CHDLC_HDRLEN;
  72
  73         switch (proto) {
  74         case ETHERTYPE_IP:
  75                 ip_print(ndo, p, length);
  76                 break;
  77         case ETHERTYPE_IPV6:
  78                 ip6_print(ndo, p, length);
  79                 break;
  80         case CHDLC_TYPE_SLARP:
  81                 chdlc_slarp_print(ndo, p, length);
  82                 break;
  83         case ETHERTYPE_MPLS:
  84         case ETHERTYPE_MPLS_MULTI:
  85                 mpls_print(ndo, p, length);
  86                 break;
  87         case ETHERTYPE_ISO:
  88                 /* is the fudge byte set ? lets verify by spotting ISO headers */
  89                 if (length < 2)
  90                     goto trunc;
  91                 if (GET_U_1(p + 1) == NLPID_CLNP ||
  92                     GET_U_1(p + 1) == NLPID_ESIS ||
  93                     GET_U_1(p + 1) == NLPID_ISIS)
  94                     isoclns_print(ndo, p + 1, length - 1);
  95                 else
  96                     isoclns_print(ndo, p, length);
  97                 break;
  98         default:
  99                 if (!ndo->ndo_eflag)
 100                         ND_PRINT("unknown CHDLC protocol (0x%04x)", proto);
 101                 break;
 102         }
 103
 104         return (CHDLC_HDRLEN);
 105
 106 trunc:
 107         nd_print_trunc(ndo);
 108         return (ND_BYTES_AVAILABLE_AFTER(bp));
 109 }
 110
 111 /*
 112  * The fixed-length portion of a SLARP packet.
 113  */
 114 struct cisco_slarp {
 115         nd_uint32_t code;
 116 #define SLARP_REQUEST   0
 117 #define SLARP_REPLY     1
 118 #define SLARP_KEEPALIVE 2
 119         union {
 120                 struct {
 121                         uint8_t addr[4];
 122                         uint8_t mask[4];
 123                 } addr;
 124                 struct {
 125                         nd_uint32_t myseq;
 126                         nd_uint32_t yourseq;
 127                         nd_uint16_t rel;
 128                 } keep;
 129         } un;
 130 };
 131
 132 #define SLARP_MIN_LEN   14
 133 #define SLARP_MAX_LEN   18
 134
 135 static void
 136 chdlc_slarp_print(netdissect_options *ndo, const u_char *cp, u_int length)
 137 {
 138         const struct cisco_slarp *slarp;
 139         u_int sec,min,hrs,days;
 140
 141         ndo->ndo_protocol = "chdlc_slarp";
 142         ND_PRINT("SLARP (length: %u), ",length);
 143         if (length < SLARP_MIN_LEN)
 144                 goto trunc;
 145
 146         slarp = (const struct cisco_slarp *)cp;
 147         ND_TCHECK_LEN(slarp, SLARP_MIN_LEN);
 148         switch (GET_BE_U_4(slarp->code)) {
 149         case SLARP_REQUEST:
 150                 ND_PRINT("request");
 151                 /*
 152                  * At least according to William "Chops" Westfield's
 153                  * message in
 154                  *
 155                  *      https://web.archive.org/web/20190725151313/www.nethelp.no/net/cisco-hdlc.txt
 156                  *
 157                  * the address and mask aren't used in requests -
 158                  * they're just zero.
 159                  */
 160                 break;
 161         case SLARP_REPLY:
 162                 ND_PRINT("reply %s/%s",
 163                         GET_IPADDR_STRING(slarp->un.addr.addr),
 164                         GET_IPADDR_STRING(slarp->un.addr.mask));
 165                 break;
 166         case SLARP_KEEPALIVE:
 167                 ND_PRINT("keepalive: mineseen=0x%08x, yourseen=0x%08x, reliability=0x%04x",
 168                        GET_BE_U_4(slarp->un.keep.myseq),
 169                        GET_BE_U_4(slarp->un.keep.yourseq),
 170                        GET_BE_U_2(slarp->un.keep.rel));
 171
 172                 if (length >= SLARP_MAX_LEN) { /* uptime-stamp is optional */
 173                         cp += SLARP_MIN_LEN;
 174                         sec = GET_BE_U_4(cp) / 1000;
 175                         min = sec / 60; sec -= min * 60;
 176                         hrs = min / 60; min -= hrs * 60;
 177                         days = hrs / 24; hrs -= days * 24;
 178                         ND_PRINT(", link uptime=%ud%uh%um%us",days,hrs,min,sec);
 179                 }
 180                 break;
 181         default:
 182                 ND_PRINT("0x%02x unknown", GET_BE_U_4(slarp->code));
 183                 if (ndo->ndo_vflag <= 1)
 184                     print_unknown_data(ndo,cp+4,"\n\t",length-4);
 185                 break;
 186         }
 187
 188         if (SLARP_MAX_LEN < length && ndo->ndo_vflag)
 189                 ND_PRINT(", (trailing junk: %u bytes)", length - SLARP_MAX_LEN);
 190         if (ndo->ndo_vflag > 1)
 191             print_unknown_data(ndo,cp+4,"\n\t",length-4);
 192         return;
 193
 194 trunc:
 195         nd_print_trunc(ndo);
 196 }